The control of furnace air volume as a function of measured exhaust gas values with a measured data receiver positioned on the exhaust gas side of a furnace is known. However, there exists a disadvantage in that after a change in volume of supply air occurs, the values corresponding to the changed supply air volume can only be measured when the change has become noticeable in the exhaust gas, a process taking several seconds. This is especially disadvantageous in view of changes in the burner load, occurring comparatively rapidly and causing very fast changes in oxygen values and the characteristic curve of the valve position for changing the furnace air volume.